Self-setting calcium phosphate cements and methods for preparing and using them
AssigneeAmerican Dental Association Health Foundation
InventorsLaurence C. Chow, Shozo Takagi
Life of this patent
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Abstract
The invention includes methods and compositions relating to calcium phosphate cements, which self-harden substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium. More specifically the cements comprise a combination of one or more sparingly soluble calcium phosphates other than tetracalcium phosphate with an aqueous solution adjusted with a base to maintain a pH of about 12.5 or above and having sufficient dissolved phosphate salt to yield a solution mixture with phosphate concentration equal to or greater than about 0.2 mol/L.
Claims33
A method for making a calcium phosphate cement which self-sets to hydroxyapatite as the predominant product at ambient temperatures comprising (1) preparing an aqueous solution of phosphate having a concentration of about 0.2 mol/L or above and adjusting the pH of the solution with base to about 12.5 or above, and (2) combining the aqueous solution with a calcium phosphate salt having a calcium to phosphorus molar ratio of less than 5 to 3 which is other than tetracalcium phosphate, and with an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide, in the absence of solid crystalline phosphoric acid.
A method for making a calcium phosphate cement which self-sets to hydroxyapatite as the predominant product at ambient temperatures comprising preparing a mixture of a calcium phosphate salt having a calcium to phosphorus molar ratio of less than 5 to 3 which is other than tetracalcium phosphate, an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide, water, a non-calcium containing phosphate salt at a concentration of about 0.2 mols/L or above and base effective to adjust the pH to about 12.5 or above, in the absence of solid crystalline phosphoric acid.
A method for making a calcium phosphate cement which self-sets to hydroxyapatite as the predominant product at ambient temperatures comprising combining a calcium phosphate salt consisting essentially of dicalcium phosphate or dicalcium phosphate dihydrate, with an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide and an aqueous solution adjusted with base to maintain a pH of about 12.5 or above.
A method for making a calcium phosphate cement which self-sets to hydroxyapatite as the predominant product at ambient temperatures comprising preparing a mixture of a calcium phosphate salt consisting essentially of dicalcium phosphate or dicalcium phosphate dihydrate, an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide, water and base effective to maintain a pH of about 12.5 or above.
A method for making a calcium phosphate cement which self-sets to hydroxyapatite as the predominant product at ambient temperatures comprising (1) preparing an aqueous solution of a non-calcium containing salt of phosphoric acid having a concentration of phosphate of about 0.2 mols/L or above, and (2) combining the aqueous solution with a calcium phosphate salt having a calcium to phosphorus molar ratio of less than 5 to 3 which is other than tetracalcium phosphate, and with an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide, in the absence of solid crystalline phosphoric acid.
A method for making a calcium phosphate cement which self-sets to hydroxyapatite as the predominant product at ambient temperatures comprising preparing a mixture of a calcium phosphate salt having a calcium to phosphorus molar ratio of less than 5 to 3 which is other than tetracalcium phosphate, an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide, water and a non-calcium containing salt of phosphoric acid at a concentration of phosphate of about 0.2 mols/L or above, in the absence of solid crystalline phosphoric acid.
A calcium phosphate composition which self-hardens to hydroxyapatite as the predominant product at ambient temperature comprising a calcium phosphate salt having a calcium to phosphorus molar ratio of less than 5 to 3 which is other than tetracalcium phosphate, an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide, and an aqueous phosphate solution of pH about 12.5 or above with phosphate concentration of about 0.2 mol/L or above, in the absence of solid crystalline phosphoric acid.
A calcium phosphate composition which self-hardens to hydroxyapatite as the predominant product at ambient temperature comprising a calcium phosphate salt having a calcium to phosphorus molar ratio of less than 5 to 3 which is other than tetracalcium phosphate, an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide, water, phosphate salt at a concentration of about 0.2 mols/L or above and base effective to maintain the pH at 12.5 or above, in the absence of solid crystalline phosphoric acid.
A calcium phosphate composition, which self-hardens to hydroxyapatitc as the predominant product at ambient temperature, comprising a calcium phosphate consisting essentially of dicalcium phosphate or dicalcium phosphate dihydrate, an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide and an aqueous solution having a pH of about 12.5 or above.
A calcium phosphate composition, which self-hardens to hydroxyapatite as the predominant product at ambient temperature, comprising a calcium phosphate consisting essentially of elicalcium phosphate or dicalcium phosphate dihidrate, an additional source of calcium selected from the group consisting of calcium carbonate calcium oxide and calcium hydroxide, water and a base effective to adjust the pH to about 12.5 or above.
A calcium phosphate composition, which self-hardens to hydroxyapatite as the predominant product at ambient temperature, comprising a calcium phosphate salt having a calcium to phosphorus molar ratio of less than 5 to 3 which is other than tetracalcium phosphate, an additional source of calcium selected from the the group consisting of calcium carborate, calcium oxide and calcium hydroxide, and an aqueous phosphate solution of a non-calcium containing salt of phosphoric acid with phosphate concentration of about 0.2 mols/L or above in the absence of solid crystalline phosphoric acid.
A calcium phosphate composition, which self-hardens to hydroxyapatite as the predominant product at ambient temperature, comprising a calcium phosphate salt having a calcium to phosphorus molar ratio of less than 5 to 3 which is other than tetracalcium phosphate, an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide, water and a non-calcium containing salt of phosphoric acid at a concentration of about 0.2 mols/L or above in the absence of solid crystalline phosphoric acid.
A self-setting calcium phosphate bone cement comprising a mixture of (1) calcium phosphate salt having a calcium to phosphorus molar ratio of less than 5 to 3 which is other than tetracalcium phosphate, (2) an additional source of calcium selected from the group consisting of calcium carbonate, calcium oxide and calcium hydroxide, and (3) an aqueous phosphate solution of pH of about 12.5 or above with a concentration of phosphate of about 0.2 mols/L or above, in the absence of solid crystalline phosphoric acid.
Dependencies are inferred from the claim text.